The enzymatic methods currently used for labeling DNA probes with either radioactive or non-radioactive compounds are lengthy, time-consuming and costly. The aim of this study is to develop commercially feasible chemical methods for labeling DNA probes with non-radioactive compounds, such as biotin and fluorescent labels. These chemical procedures will enhance the potential of DNA probes technologies by making it easier to produce probes on a large scale. We developed a simple, rapid chemical method for labeling mononucleotides and single-stranded DNA in Phase I. The feasibility of using chemically labeled single-stranded DNA probes for in situ, dot blot and microtiter plate assays was demonstrated. Chemical methods for labeling double-stranded DNA and oligonucleotide probes will be developed in Phase II, based on these Phase I studies. A one-step chemical method for labeling double-stranded DNA will also be developed. The commercial potential and clinical relevance of the probes produced using these novel chemical labeling procedures will be evaluated on the basis of their sensitivity, cost, and the ease and reliability of their production.